memory-util: add a concept for gcc cleanup attribute based array destruction

src/basic/alloc-util.h

@@ -15,6 +15,7 @@
 
 typedef void (*free_func_t)(void *p);
 typedef void* (*mfree_func_t)(void *p);
+typedef void (*free_array_func_t)(void *p, size_t n);
 
 /* If for some reason more than 4M are allocated on the stack, let's abort immediately. It's better than
  * proceeding and smashing the stack limits. Note that by default RLIMIT_STACK is 8M on Linux. */

src/basic/memory-util.h

@@ -111,3 +111,37 @@ static inline void erase_and_freep(void *p) {
 static inline void erase_char(char *p) {
         explicit_bzero_safe(p, sizeof(char));
 }
+
+/* An automatic _cleanup_-like logic for destroy arrays (i.e. pointers + size) when leaving scope */
+struct ArrayCleanup {
+        void **parray;
+        size_t *pn;
+        free_array_func_t pfunc;
+};
+
+static inline void array_cleanup(struct ArrayCleanup *c) {
+        assert(c);
+
+        assert(!c->parray == !c->pn);
+
+        if (!c->parray)
+                return;
+
+        if (*c->parray) {
+                assert(c->pfunc);
+                c->pfunc(*c->parray, *c->pn);
+                *c->parray = NULL;
+        }
+
+        *c->pn = 0;
+}
+
+#define CLEANUP_ARRAY(array, n, func)                                   \
+        _cleanup_(array_cleanup) _unused_ struct ArrayCleanup CONCATENATE(_cleanup_array_, UNIQ) = { \
+                .parray = (void**) &(array),                            \
+                .pn = &(n),                                             \
+                .pfunc = (free_array_func_t) ({                         \
+                                void (*_f)(typeof(array[0]) *a, size_t b) = func; \
+                                _f;                                     \
+                        }),                                             \
+        }